Contents lists available at ScienceDirect Journal of Photochemistry & Photobiology A: Chemistry journal homepage: www.elsevier.com/locate/jphotochem Evidence of non-photo-Fenton degradation of ibuprofen upon UVA irradiation in the presence of Fe(III)/malonate Besma A. Dekkiche a , Nadra Debbache a, ⁎ , Imane Ghoul a , Nassira Seraghni a , Tahar Sehili a , Zenydia Marín b , J. Arturo Santaballa b , Moisés Canle b, ⁎ a Laboratoire des Sciences et Technologies de l’Environnement, Université Frères Mentouri, Constantine 1, Algeria b Universidade da Coruña, Grupo Reactividade Química e Fotorreactividade, Departamento de Química, Facultade de Ciencias & CICA, E-15071 A, Coruña, Spain ARTICLE INFO Keywords: Fe(III)-malonate complexes Acetate radical Ibuprofen Photodegradation photoFenton ABSTRACT The degradation of ibuprofen (IBP) in the presence of the complex Fe(III)-malonate in aqueous solution under 365 nm radiation has been investigated. Photolysis of Fe-malonate mainly generates the % CH 2 COOH radical, instead of HO % radicals. This is contrary to the generally observed behaviour with other iron-carboxylate complexes, where H 2 O 2 is produced and HO % radicals are generated. The photodegradation of the IBP/Fe(III)- malonate/UVA system is slower than expected because the photo-Fenton reaction takes place only to a limited extent. Reaction rate profiles show an induction period, and IBP/Fe-malonate system runs inversely to Fe(II) formation. Almost complete IBP disappearance takes place after five hours with [IBP] 0 = 0.05 mM, [Fe (III)] = 0.3 mM, [malonate] 0 = 1.2 mM, pH = 2.8, λ irr = 365 nm, T ca. 293 K. Kinetic profiles resemble first order decays as [H 2 O 2 ] increases, and both the efficiency of the process and the reaction rate increase with acidity. Addition of Ca(II), Mg(II) and Mn(II) to the system IBP/Fe(III)-malonate/UVA has no effect on the degradation, whereas Cu(II) slightly inhibits it. Transformation photoproducts are more difficult to photo- degrade than the mixture itself, only ca. 40% TOC disappears after 360 min and 64% COD is removed after 24 h of irradiation (IBP/Fe(III)-malonate/UVA system). Seven transformation photoproducts were identified by HPLC-MS and the corresponding reaction mechanism has been proposed. Sunlight irradiation improves the reaction, showing the feasibility of IBP photodegradation in natural environments under carefully controlled conditions. 1. Introduction Pharmaceuticals are a group of emerging organic compounds of high environmental concern, used extensively in human and veterinary medicine. These compounds enter directly the hydrosphere via sewage and / or inappropriate disposal [1]. Concentrations of pharmaceutical residues measured in natural waters are typically in very low con- centrations (pg/L or ng/L–μg/L range). However, many of these are considered persistent organic pollutants due to their continual replen- ishment [2]. Pharmaceuticals and their metabolites entering the aquatic environment have potential harmful effects on human health, the aquatic ecosystem and can reach drinking water resources [3–5]. Non-steroidal anti-inflammatory drugs (NSAIDs) constitute a group of widely used pharmaceuticals, with more than 70 million annual pre- scriptions in the world [6]. Ibuprofen (2-(4-(2-methylpropyl)phenyl)propanoic acid) is a NSAIDs, one of the most consumed in the world [7]. Ibuprofen (IBP) is worldwide found in the aquatic environment with concentrations up to ca. 300 μgL -1 [8]. There is a growing concern about the effects of pharmaceutical pollution by the most consumed drugs [9]. Although IBP can be biologically degraded [10], the environmental risk of its presence in water remains high. Its transformation products show si- milar toxicological effects to those of IBP [11]. Some researchers sug- gested that IBP may alter the post-embryonic development of anuran (amphibia) in freshwater environments [12], and it has been reported that IBP contamination is actually affecting fish in 50 percent of rivers that have been studied [13]. Thus, quantitative evaluation of the fate of pharmaceuticals, proper risk assessment and improvement of the effi- ciency of wastewater treatment processes need further study. Persistent organic pollutants, including IBP, are usually refractory to biological and classic water treatments. Advanced Oxidation Processes (AOPs) have proved efficient for their elimination. Various treatment techniques have been evaluated for IBP removal from the aqueous medium, such as photolysis [14,15], ozonation [16,17], UVA https://doi.org/10.1016/j.jphotochem.2019.111976 Received 15 April 2019; Received in revised form 12 July 2019; Accepted 15 July 2019 ⁎ Corresponding authors. E-mail addresses: nadradebbache@yahoo.fr (N. Debbache), mcanle@udc.es (M. Canle). Journal of Photochemistry & Photobiology A: Chemistry 382 (2019) 111976 Available online 16 July 2019 1010-6030/ © 2019 Elsevier B.V. All rights reserved. T